Variable volume hydraulic pump or motor



Feb. 27, 1962 R. w. BRUNDAGE 3,022,741

VARIABLE VOLUME HYDRAULIC PUMP 0R MOTOR Filed May 6, 1957 2 Sheets-Sheet 1 FIG. I

ATTORNEY Feb. 27, 1962 R. w. BRUNDAGE 3,022,741

' VARIABLE VOLUME HYDRAULIC PUMP OR MOTOR Filed May 6, 1957 2 Sheets-Sheet 2 INVEN ROBERT W. BRUND ATTORNEY United States Patent ()fifice 3,022,? Patented Feb. 27, 1962 3,022,741 VLE VOLUME HYDRAULIC PUMP R MOTGR Robert W. Brundage, Willoughby, Qhio (2809 Wakonda Drive, Belnor, St. Louis, Mo.) Filed May 6, 1957, Ser. No. 657,314 14 Claims. (Cl. 193-120) This invention pertains to the art of hydraulic pumps or motors and more particularly to hydraulic pump or motor of the variable volume type.

The invention is particularly applicable to a. hydraulic pump of the internal gear type and will be described with particular reference thereto although it will be appreciaated that the invention is equally applicable to internal gear hydraulic motors or to other pumps or motors wherein the chambers rotate, such as, without limitation, vane type or rotating-cylinder barrel type pumps or motors.

While the invention will be described and claimed as directed to a pump, it will be appreciated that the terminology herein is equally applicable to a motor if the terms inlet and inlet pressures are considered as being discharge or discharge pressures and the terms outlet or outlet pressures are considered as inlet or inlet pressures. Pumps of the type to which this invention pertains normally comprise a plurality of relatively movable members which define a plurality of closed rotating increasing and decreasing volume chambers which alternately communicate through rotating passages with inlet and outlet manifolds sealingly separated by a pair of lands which engage surfaces on the members between the passages and prevent fluid flow between the manifolds.

These lands are ordinarily of a carefully controlled circumferential width greater than the circumferential width of the passages leading from the chambers to the manifolds. Leakage of high pressure fluid is thus prevented around the lands and through the passages when a passage faces a land.

The lands are ordinarily located on the neutral axis through the points of maximum and minimum volume of the chambers. It is known that the output volume of a hydraulic pump or the speed of a motor may be varied by adjusting the lands away from this neutral axis.

In my co-pending application, Serial No. 497,779, filed March 29, 1955, now US. Patent No. 2,898,862, issued August 11, 1959, an arrangement is described wherein the output volume of a pump may be varied by rotating only the land disposed opposite the point of minimum volume of the chambers for full volume past the increasing volume chambers. Such an arrangement ofiers substantial advantages over moving both lands. As now appears, one disadvantage is present, namely that because of interference with the other land (which was fixed), the movable land could not be adjusted to zero output volume.

The present invention contemplates a pump (or motor) which overcomes the above difiiculties and enables the output volume of the pump with one adjustable stop to be readily varied from a maximum to zero.

In accordance with the present invention, a hydraulic pump (or motor) is comprised of: a plurality of members defining a plurality of revolving, increasing and decreasing volume chambers; input and outlet manifolds communicating alternately with such chambers as they revolve and separated by a pair of lands; one land being adjustable from a full volume position at one end of the neutral axis through the minimum and maximum volume positions of the chambers toward the opposite end to reduce the output volume of the pump to zero, the other land being normally fixed but so arranged that the movable land may be adjusted to the minimum or zero volume position.

Thus, at the zero volume position, both lands are symmetrically arranged about one end of the neutral axis which means that the other land is ofiset from such neutral axis. This other land may be permanently offset from the neutral axis or movable therefrom as the adjustable land is moved to the zero volume position.

Further, in accordance with the invention, the normally fixed land is of a width wider than the passages leading from the chambers, and if such land is to be positioned opposite decreasing volume chambers, it is provided with a trapping port dividing the land into a pair of auxiliary lands of a width less than the passage leading from the chambers and means are provided for bleeding such trapping port to the low pressure manifold when the land is positioned opposite a decreasing volume chamber.

Further, in accordance with the invention, the adjustable land when adjustable over the arc of decreasing volume chambers or when the increasing volume chambers leaving the adjustable land come into communication with the high pressure manifold, a similar trapping port is provided on the adjustable land in combination with means for maintaining the pressure in the trapping port at approximately one half the high pressure. '1 nus, such means, when the adjustable land is movable over the arc of decreasing volume chambers, must bleed fluid to the inlet manifold. In the other case when the increasing volume chambers leave the adjustable land and come into communication with the high pressure manifold, the means will supply fluid under pressure from this manifold to the trapping port.

Using the present invention, substantial increases in volumetric efiiciency over all ranges of output volume can be obtained over the use of a straight bypass to control the output volume and substantial increases in volumetric efficiency at low volume outputs can be obtained over that described in my copending application, Serial No. 548,022, filed November 21, 1955, now US. Patent No. 2,956,506, issued October 18, 1960.

The principal object of the invention is the provision of a new and improved hydraulic pump (or motor) which overcomes all the difliculties of the prior art, provides for ready adjustment of the output volume, has a high volumetric efiiciency, and a high mechanical efliciency.

Another object of the invention is the provision of a new and improved hydraulic pump wherein one of the lands only may be adjusted to control the output volume and the other lands arranged to move from its normally fixed position where it would interfere with adjustment of the first stop.

Another object of the invention is the provision of a new and improved hydraulic pump which is relatively simple in construction, economical to manufacture, and has provision for providing a desired pressure gradient across the sealing faces of the stops.

The invention may take physical form in certain parts and arrangement of parts, preferred embodiments of which will be described in this specification and illustrated in the accompanying drawing which is a part hereof and wherein:

FIGURE 1 is a side cross-sectional view of a variable volume hydraulic pump illustrating a preferred embodiment of the invention.

FIGURE 2 is a cross-sectional view of FIGURE 1 taken on the line 2-2 thereof with the gear members forming the pump shown in phantom thereover. The pump is shown as adjusted to the full volume position.

FIGURE 3 is a view similar to FIGURE 2 but without the phantom gears showing the pump adjusted to zero volume.

FIGURE 4 is a View similar to FIGURE 2 but showing an alternative embodiment of the invention adjusted to the full volume position.

FIGURE 5 is a view similar to FIGURE 4, but showing the pump adjusted to the zero volume position.

FIGURE 6 is a cross-sectional view of FIGURE 1 on the line 22 showing an alternative embodiment of the invention; and

FIGURE 7 is a similar view showing the invention applied to a motor.

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purposes of limiting same, the figures show a hydraulic pump comprised. of a housing A made up of two cup-shaped facing. members 9, 10 defining a closed pump cavity 8 in which the various members of the pump are mounted. A drive shaft 11 driven from an external power source, not shown, extends into the interior of the housing A and has mounted thereon for rotation therewith, reading from left to right, a sealing disc 12, an externally toothed gear 13, and a ported plate 14. The sealing disc 12 is rigidly mounted on the shaft 11 as by an interference fit and is supported for rotation in the housing as by a roller bearing 16 axially slidable in interior of the housing and held in position on the disc 12 by means of a snap ring 5.

In like manner, the ported plate 14 is rotatably supported in a roller bearing 6 held in place in the housing by means of a snap ring 7. The ported plate 14 is axially movable within the roller bearing 6.

An internally toothed ring gear 15 having one, or more, teeth than the teeth of the gear 13 is meshed with the externally toothed gear 13 and defines therebetween a plurality of rotating progressively increasing and decreasing volume chambers 17, 18. The gear 15 is mounted. for rotation on an axis spaced from the axis of] the shaft 11 by means of a roller bearing 21 mounted in a counterbore in the housing having an axis spaced from the axis of the shaft 11 the desired amount.. The ring gear 15 is axially siidable in the bearing 21.

The gear 13 and the ported plate 1'4 are keyed to rotate with the. shaft 11' as by means of the key 22 and the pin 23 but both members are axially slidable on the shaft 11..

Means, as will appear hereinafter, holds these members in side by side engagement so that the sealing disc 12' sealingly engages the left hand surfaces of the gears 13, 15 to close the left hand end of the chambers 17, 18 while the ported plate 14 is in sealing engagement with the right hand end of the gears 13, 15.

The ported plate 14 has a plurality of passages 25 which when considered in a direction toward the chambers 17,. 1'8 slope outwardly and away from the direction of rotation. One passage 25 is provided for each chamber 17, 18 and fiuid going to and from the chambers 17, 18. passes through the passages 25. The use of the ported plate 14 and the function of the sloping of the passages 25 is more fuliy described in my co-pending application, Serial No. 613,235, filed October 1, 1956 and will not be further detailed herein.

A sleeve 26 surrounds the shaft 11 to the left of the sealing disc 12 and has a radially outwardly extending flange 27 to provide; a pressure surface 28 on which fluidv pressure (as will appear) in the cavity 8 may exert an axial force to the right to hold the right hand surface of the sleeve 26 in sealing engagement with the disc 12. The sleeve 26 is reciprocably mounted in a counterbore 29 in the left hand of the housing A and an O-ring 30 seals its outer surface. A compression spring 31 bears against the base of the counterbore 29 and against the left hand of the sleeve 27 to provide an initial sealing force of the sleeve 26 on the sealing disc 12. The area of the surface 28 is so proportioned that the sealing force between the surfaces is suificient to prevent the leakage of hydraulic fluid from the cavity 8 between the surfaces and thus outwardly along the shaft 11. The construction and operation of the sleeve 26 is described and claimed in my co-pending application, Serial No, 613,235, filed October 1, 1956, and will not be described further herein. Sufice it to say, that the pump cavity 8 is closed and under hydraulic pressure.

In accordance with the present invention, the pump also includes arcuately extending inlet and outlet manifolds 35, 36 opening toward the ported plate 14 and each adapted to be simultaneously in communication with one or more of the passages 25, the number being variable so that the output volume of the pump may also be varied.

The inlet and outlet manifolds are sealingly separated at the arcuate ends by what may be termed a fixed land 38 and an adjustable land 39 both having their left hand surface in sealing engagement with the right hand surface of the ported plate 14. Thus the chambers 17, 18 each have a passage 25' opening through a rotating sealing surface and the manifolds open through sealing surfaces, both of which surfaces are in sealing engagement.

The inlet manifold 35. extends axially and communicates with a passage 40 in the right hand base of the housing A which communicates with radially outward extending passage 41 to the outside of the housing A,

The outlet manifold 36 also extends axially of the housing A and communicates with an outlet or discharge passage 43 in the right hand base of the housing A" which in turn communicates with a radially outward extending passage 44 to the external surface of the housing.

As will be seen from FIGURE 2, the discharge passage 43 is located adjacent to the point of minimum volume of the chambers. 17, 18, but spaced therefrom slightly opposite to the direction of rotation.

In a like manner, the inlet passage 40 is located adjacent to the point of maximum volume of the chambers 17, 18 and spaced slightly therefrom in a direction opposite to the direction of rotation. The total diameter of passage 40 is so adjusted that when the lands 38, 39 are in the position as shown in either FIGURES 2 or 3, the passage 40 will not be, in communication with the outlet manifold 36.

With the lands positioned as shown in FIGURE 2, i.e.', at the points of minimum andmaximum chamber volume, the pump will have full volume output. These points of minimum and maximum volume define what may betermed as the neutral axisof the pump. With the lands adjusted as shown in FIGURE 3, the pump will have zero To obtain such variation in volume, the

volume output. land 39 is adjustable from the position in FIGURE 2 that is from the neutral axis adjacent the point of zero chamber volume over the increasing volume chambers thus exposing the increasing volume chambers 17 to the presnated as; a fixedland, is mounted for movement a slight.

distance. clockwise as viewed in FIGURE 3 so that the output volume. of. the. pump can bereduced to zero.

While the mounting and arrangements of the lands 38, 39 to permit this may be as desired, in the embodiments shown, the land 39 is in the form of a lug extending axially on a shaft 45. Any cavitation which might occur as the increasing volume chamber approaches the maximum volume point is low or any that does occur is offset by the decrease in volume of the chambers after it passes the point of maximum volume.

However, with the fixed land being movable away from the point of maximum volume, means must be provided to prevent trapping. Such means comprise a trapping port 65, centrally located in the face of the land 38, extending radially inwardly to the inner surface of the land 38. The trapping port 65 communicates with a groove or passage 66 on the outer surface of the shaft 45 adjacent to the adjustable land 39 on the side in the direction or rotation and communicating with the inlet manifold. As the land 39 comes into contact with the land 38, the trapping port 65 is communicated to the inlet manifold 35. Trapping is prevented.

The trapping port 65 in efiect divides the fixed land 38 into two auxiliary lands 38a and 38b both of which have a circumferential width just less than the circumferential width of the passages 25.

In the embodiments shown in FIGURES 2 and 3, the adjustable land 39 moves from a maximum volume position opposite the point of zero volume of the chambers 17 over the arc of the increasing volume chambers.

The arcuate width of the land 39 is wider than the width of the passages 25. Thus, as a passage 25 moves under the land 39, cavitation in the corresponding increasing volume chamber will occur. However, as this chamber with the cavitation moves from under the land, it comes into communication with the inlet manifold and no, problems are presented.

In the embodiments shown in FIGURES 4 and 5, however, the land 39 is adjustable from a full volume position opposite the point of maximum volume of the chambers (see FIGURE 4) over the arc of the increasing volume chambers to the zero volume position (see FIGURE 5). In this embodiment, cavitation will also occur within the chambers, but here the chambers with the cavitation move into communication with the high pressure manifold. This is undesirable. Thus in accordance with the invention, the land 39 is provided with a trapping port 70 which divides the land 39 into two auxiliary lands of a width less than the width of the passages 25 so that cavitation will not occur. Means have been provided for supplying hydraulic fiuid to the trapping port 70 at a pressure equal approximately to one-half the high pressure fluid. In the embodiment of the invention shown, the trapping port 70 communicates with the high pressure manifold through passage 71 and a pressure valve consisting of a chamber 72 in the member 45, a valve seat 75 screwed into this chamber, and a ball 73 held in engagement with the valve seat by a spring 74. The tension of the spring 74 is so adjusted as to maintain a pressure in the trapping port 70 generally equal to one-half the pressure in the high pressure manifold.

The trapping port 70 is also shown in connection with the embodiment in FIGURE 3, although for the reasons above indicated, namely that cavitation is not a problem in this embodiment, the trapping port 70 and pressure valve may be conveniently omitted.

In the embodiments of the invention described, it will be appreciated that the pressure in the high pressure manifold on the sides of the fixed land 38 normally urges the fixed land to a position on the neutral axis through the chambers, and the adjustable land moves over the arc of the increasing volume chambers, and when it reaches the fixed land, it moves the fixed land from this position.

In some cases, it is desirable to move the adju table land over the arc of the decreasing volume chambers, as shown in FIGURE 6. In such a case, the pressure in the high-pressure manifold urges the land 38 in the same direction that the adjustable land would move it when it moved to the zero volume position. In this embodiment of the invention, the fixed land 38 is permanently positioned offset from the neutral axis in the direction of rotation from the point of minimum volume of the chambers. Some cavitation will occur underneath the land 38, as so positioned in FIGURE 6, but as previously indicated, the chamber with the cavitation will subsequently come into communication with the low pressure manifold, and no harm will result.

It is to be noted that in FIGURE 6, the trapping port 65 has been omitted as unnecessary.

However, the adjustable land 39 must have the trapping port 74) provided therein, and meansare provided for maintaining the pressure in this trapping port at approximately one-half the high pressure. However, in the embodiment shown in FIGURE 6, fluid will be supplied to the trapping port, and the pressure regulating valve shown is similar to that shown in FIGURES 1, 4 and 5 with the exception that the valve seat 75 is at the base of the valve chamber so that fluid may be bled from the trapping port 70 to the low pressure manifold.

FIGURE 7 shows the invention applied to a variable speed hydraulic motor wherein the output speed of the motor is adjusted by positioning one of the lands. In the case of a motor for'the same direction of rotation, the inlet manifold becomes the high pressure manifold. In this embodiment of the invention, the fixed land 38 is offset from the neutral axis opposite the point where the chambers of the maximum volume in a direction opposite to the rotation. Thus, the increasing volume chambers as they leave the fixed land 33 come into comr'nunication with the low pressure. Cavitation is not a problem. The adjustable land 39 is adjustable over the arc of the decreasing volume chambers to a point adjacent the neutral axis where the chambers of a maximum volume for zero speed of rotation of the motor. In this case, the adjustable land 39 moving over a decreasing volume chamber must have the pressure relief valve so arranged as to bleed fluid from the trapping port 70 to the low pressure manifold. I

It will be seen that to change the embodiment of FIG- URE 6 from a pump to a motor, as shown in FIGURE 7, the fixed land has been shifted from an offset in the direction of rotation from the point of minimum volume to an offset opposite the direction of rotation from the point of maximum volume.

If the embodiment of FIGURE 3 is to be employed as a motor, the land 38 would be shifted so as to be opposite the decreasing volume chambers, but oifset from the neutral axis adjacent the point of minimum volume of the chambers against the direction of rotation.

Thus, it will be seen that in accordance with the invention, a hydraulic pump or motor of the variable voltime or speed type has been provided wherein one of the lands is adjustable to vary the volume or speed, and the other land is so arranged relative to the neutral axis of the pump that the adjustable stop may be moved to either the zero volume or speed position. Further, it will be seen that in some instances it is possible to position a land in a permanently offset position, While in other cases, it is possible to arrange the fixed land so that it may move to this position from a normal position on the neutral axis.

The invention has been described with reference to preferred embodiments. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification, and it is my intention to include all such modifications and alterations insofar as they come within the scope of the appended claims.

Having this described my invention, I claim:

1. A positive displacement hydraulic device comprised of a plurality of members movable relatively to each other and defining a plurality of chambers revolving in a fixed closed path of movement, said chambers gradually increasing in volume after they pass a fixed point of minimum volume on said path of movement until they reach a fixed point of maximum volume on said path of movement and then gradually decreasing in volume until they reach said fixed point of minimum volume, means defining an arcuate inlet and an arcuate outlet manifold including first and second lands, one at each arcuate end of said manifolds and sealingly separating said manifolds one fom the other, an opening for each chamber revolving therewith, each of said openings moving past said lands to alternately communicate its associated chamber with either said inlet or said outlet manifold, said first land being normally located at the point of maximum volume so that as each chamber reaches and passes through maximum volume, its opening shifts from communication with one manifold to the other manifold, said second land being adjustable independently of said first land along the path of movement of said chambers from the point of minimum volume to the point of maximum volume so as to change the point in the path of movement in which each opening moves past said second land and shifts communication of its chamber from one manifold to the other, the improvement which comprises said first land is movable from the point of maximum volume to allow said second land to be adjusted to a point adjacent the point of maximum volume.

2. The improvement of claim 1 wherein means are provided for biasing said first land towards said point of maximum volume.

3. The combination of claim 1 wherein hydraulic pressure in the output manifold urges said first land toward the point of maximum volume.

4. The improvement of claim 1 wherein said first land has a trapping port dividing said land into two auxiliary lands and means are providedrfor communicating said trapping port with one of said manifolds as said first land is adjusted from said point of maximum volume.

5. The improvement of claim I wherein said second land has a pressure groove which communicates with each opening as said opening moves past said second land and means are provided for maintaining said groove at a pressure approximately one half the pressure in the high pressure manifold.

6. The improvement of claim 5 wherein said second land is adjustable along the path of movement of said increasing volume chambers and said means include a pressure reducing valve communicating the high pressure manifold of said device with said groove.

7. A hydraulic device comprised of a plurality of members movable relatively to each other and defining a plurality of chambers revolving in a fixed closed path of movement, said chambers gradually increasing in volume after they pass a fixed point of minimum volume on said path of movement until they reach a fixed point of maximum volume on said path of movement and then gradually decreasing in volume until they reach said fixed point of minimum volume, means defining an armate inlet and an arcuate outlet manifold including first and second lands, one at each arcuate end of said manifold and sealingly separating said manifolds one from the other, an opening for each chamber revolving there-. with, each of said openings moving past said lands to alternately communicate its associated chamber with either said inlet or said outlet manifold, one of said manifolds being at high hydraulic pressure, the improvement which comprises: said first land being adjustable along the path of movement of said chambers and having a line of movement width greater than said openings, said first land having a trapping port communicating with each opening as said opening moves past said first land, said trapping port dividing said first land into a pair of auxiliary lands, each having a line of movement width equal to or less than the line of movement width of said openings, and means for maintaining said trapping ports 8.. ate pressure approximately equal to. one half the pressure in the high pressure manifold.

8. The improvement of claim 7 wherein said first land is adjustable along the line of movement of the increasing volume chambers and said means consist of a pressure valve arranged to admit fluid from the high pressure manifold to said trapping port 9. The improvement of claim 7 wherein said first land is adjustable along the line of movement of said decreasing volume chambers and said means consist of a pres sure relief valve arranged to, bleed fluid from said trapping port tothe low pressure manifold.

10. A variable volume or speed hydraulic pump or motor respectively comprised of: a housing; a plurality of rotatable members defining a plurality of chambers which revolve in a fixed closed path of movement, said chambers gradually increasing in volume after they have passed a fixed point of minimum volume on said path of movement until they reach a fixed point of maximum volume on said path of movement and then gradually decreasing in volume until they reach said fixed point of minimum volume, means defining an arcuate inlet and an arcuate outlet manifold including first and second lands, one on each arcuate end of said manifold and sealing separating said manifolds, an opening for each chamber revolving therewith, each of said openings moving past said lands to alternately communicate its associated chamber with either said inlet or said outlet manifold, one of said manifolds being at high fluid pressure, said points of minimum and maximum volume defining a neutral axis, said second land being adjustable along the path of movement of said decreasing volume chamhers, the improvement which comprises: said first land being spaced from said neutral axis along the path of movement.

11. The improvement of claim 10 wherein the spacing of said first land is in the direction of rotation of said rotating members and said device is being used as a pump.

12. The improvement of claim 10 wherein said spacing is counter to the direction of rotation of said rotating members and said device is being used as a motor.

13. The device of claim 10 including the further improvement wherein said second land is divided into two auxiliary lands with a trapping groove therebetween, said groove communicating with each opening as said opening moves past said second land and means are provided to communicate said trapping groove with the low pressure manifold, said means including a pressure relief valve.

14. A positive displacement hydraulic device comprised of a plurality .of members movable relativelvto each other and defining a plurality of chambers revolving in afixed closed path of movement, said chambers gradually increasing in volume after they pass a fixed point of minimum volume on said path of movement until they reach a fixed point of maximum volume on said path of movement and then gradually decreasing in volume until they reach said fixed point of minimum volume, means defining an arcuate inlet and an arcuate outlet manifold including first and second lands, one at each arcuate end of said manifolds and sealingly separating said manifolds one from the other, an opening for each chamber revolving therewith, each of said openings moving past said lands to alternately communicate its associated chamber with either said inlet or said outlet manifold, said second land being adjustable independently of said first land along the path of movement of said chambers from the point of minimum volume to the point of maximum volume so as to change the point in the path of movement in which each opening moves past said second land and shifts communication of its chamber from one manifold to the other, the improvement which comprises: said first land being permanently fixed at a point close to but spaced from said point of maximum volume whereby said second volume.

Jensen Apr. 7, 1931 10 Topanelian May 30, 1950 De Lancey Feb. 17, 1953 Nuebling Sept. 14, 1954 Cilley Dec. 27, 1955 Nubling June 12, 1956 Nubling Mar. 19, 1957 Brundage Aug. 11, 1959 FOREIGN PATENTS Great Britain July 3, 1930 France Jan. 24, 1920 r 

